22 August 2011

Ink Blots, Ambiguity and Outcomes in the Real World

A fundamental problem with climate science in the public realm, as conventionally practiced by the IPCC, is the essential ink blot nature of its presentation. By "ink blot" I mean that there is literally nothing that could occur in the real world that would allow those who are skeptical of scientific claims to revise their views due to unfolding experience. That is to say, anything that occurs with respect to the climate on planet earth is "consistent with" projections made by the climate science community. Some scientists go further and argue that climate science cannot be shown to be incorrect based on experience because its projections are probabilistic. The result is that people tend to see in climate science other things than those that can be resolved empirically -- which fosters politicization and tribal behavior.

The ink blot nature of climate science would be a non-issue if it were a field like philosophy or cosmology in which people were debating non-empirical claims for academic interests. But climate science -- or at least a very visible part of that field -- has set forth on an evangelistic path in trying to convince the unconvinced of their views among politicians and the general public.

But the ink blot nature of climate science leaves climate scientists in a position of arguing from authority or demanding that people need "trust us." The typical mode of engagement with skeptics by many visible climate scientists is to argue how right they are (and wrong/evil the skeptics are) -- but what skeptics need instead is to hear what it would mean for climate scientists to be wrong. If one cannot be wrong, then experience cannot be used to adjudicate claims. (I am aware of various debates that have occurred about using variables such tropical tropospheric temperature trends, ocean heat content, water vapor feedback, etc. in an effort to falsify claims of climate science. While I am by no means an expert on these debates my understanding is that the climate science community argues that uncertainties/variability are so large as to make such claims not inconsistent with their views, taking us back to square one.)

Consider by way of example how the field of economics handles such situations. Ratings agencies issue ratings associated with the likelihood of default for lenders, and utilize a language very similar to that found in the IPCC. For instance, here is how S&P defines their credit ratings (PDF):

In our view, likelihood of default is the centerpiece of creditworthiness. That means likelihood of default--encompassing both capacity and willingness to pay--is the single most important factor in our assessment of the creditworthiness of an issuer or an obligation. Therefore, consistent with our goal of achieving a rank ordering of creditworthiness, higher ratings on issuers and obligations reflect our expectation that the rated issuer or obligation should default less frequently than issuers and obligations with lower ratings, all other things being equal.

Although we emphasize the rank ordering of default likelihood, we do not view the rating categories solely in relative terms. We associate each successively higher rating category with the ability to withstand successively more stressful economic environments, which we view as less likely to occur. We associate issuers and obligations rated in the highest categories with the ability to withstand extreme or severe stress in absolute terms without defaulting. Conversely, we associate issuers and obligations rated in lower categories with vulnerability to mild or modest stress.

It is generally understand that the ratings agencies were wrong in their estimates of the likelihood of default among mortgage based securities. How do we know this? Well, the global economy melted down for one.

I am aware of no one who has claimed that the ratings of subprime mortgages cannot be judged wrong simply because ratings are based on likelihood estimates. But this is exactly where some climate scientists would find themselves, if they were arguing about economics rather than climate.

When assessing the downgrade, the question of track record comes up. As I understand it, countries that defaulted in the past were almost always downgraded well before the default happened; but in all such cases, the markets were already signalling big trouble before the rating agencies moved.

The question should be, in cases when the markets aren’t signalling worry but the agencies downgrade anyway, how often are they right?

The answer, I believe, is never — not for Japan 2002, not for various European countries in the late 1990s, not for Canada 1994.

Until the climate science community steps out from behind academic parsing and hiding behind uncertainties, it will continue to be an ink blot, and one that many people evaluate using political and other non-scientific criteria.

There are two ways for the climate science community to move beyond an ink blot (if it wishes to do so). One would be to advance predictions that are in fact conventionally falsifiable (or otherwise able to be evaluated) based on experience. This would mean risking being wrong, like economists do all the time. The second would be to openly admit that uncertainties are so large that such predictions are not in the offing. This would neither diminish the case for action on climate change nor the standing of climate science, in fact it may just have the opposite effect.

The default will be the status quo, which means climate science as inkblot -- and the associated arguments from authority, "trust us" and politicization that comes along with it.